Invoke all other registered handlers only for generated code

To get more information for unhandled signals, the nested handler
might be registered to kernel. This will expose an issue in some
scenarios, for example mulit-thread case, because the art default
handler will be replaced in kernel. To solve it, other handlers are
only invoked for generated code.

Change-Id: Ifa9cf4dfdd6a0ef18f88c2e2313b545d26ed826d
Signed-off-by: jgu21 <jinghui.gu@intel.com>